Sample size The sample size depends on the magnitude of the difference in reactive hypoglycemia incidence as derived from previous studies (21) and (22). The study is designed to detect a more conservative absolute difference in the occurrence of hypoglycemia of 50%, expecting an incidence of 70% in the RYGB group versus an incidence of 20% in the SG group. A sample size of 19 patients per group would be required for this clinical trial to detect an improvement data significance level of 0.05 and a power of 0.90. Considering an attrition rate of 25% over the course of the study a total of 50 subjects (25 for each group) will be enrolled.